The invention concerns an oil-sealed vane-type rotary vacuum pump with the characteristics of patent claim 1.
A vacuum pump with the characteristics of patent claim 1 is known from DD-A-256540. Laid open in this publication is a single-stage vane-type rotary vacuum pump, the rotor of which is suspended at both its ends by means of a journal bearing. The two journals as well as the related bearing sections are equipped with bores which are so formed and arranged that they act like cocks which control the entry and discharge of an excess oil flow passing through the space between the vanes. The arrangement, or the way in which the bores are assigned, is so selected that the oil enters the space between the vanes via the first journal when the space has attained its greatest volume. During this phase, and also during the subsequent phase during which the volume of the intermediate space reduces, the discharge of oil in the direction of the oil sump is blocked. Thus an increased oil pressure builds up in the space between the vanes, so that oil may enter into the suction chamber through slots which are present between the vanes and the slots in the vanes and in the area of the face sides of the rotor so that said suction chamber is supplied with the necessary sealing and lubricating oil. Shortly before the space between the vanes attains its smallest volume, the oil discharge ahead of the second journal is opened. Owing to the pumping action of the space between the vanes, the excess oil is ejected and is returned to the oil sump.